This invention relates to an apparatus for kneading rubber-like material in a chamber with rotors.
In general, rubber for manufacturing wheel tires is put in the chamber of such a kneading apparatus together with chemicals such as for instance carbon, and kneaded with a pair of rotors, so that the plasticity is decreased while the chemicals are uniformly dispersed.
A conventional rubber-like material kneading apparatus of this type comprises: a case having a chamber which is substantially cocoon-shaped in section; and a pair of rotors laid horizontally in the chamber, each rotor having two long vanes which are arranged at equal angular intervals and extended radially outwardly. Rubber blocks and chemicals in the chamber are kneaded by rotating the rotors in such a manner that the long vanes of one of the rotors are engaged with those of the other.
However, the conventional apparatus is disadvantageous in that it takes a relatively long time to uniformly disperse the chemical.
For the purpose of eliminating the difficulty, a four-vane type rotor has been proposed in which short vanes are extended from the long vanes, respectively, in such a manner that they are sloped in a direction opposite to that of the long vanes. However, even with a kneading apparatus with the four-vane type rotors, the kneading time cannot be shortened as expected; that is, it still takes a relatively long period of time to accomplish the kneading operation. If the kneading operation is continuously carried out for a long time, then the temperature of the rubber being kneaded rises, as a result of which the rubber is changed in quality for instance by vulcanization reaction Accordingly, heretofore when the temperature of the rubber increases to a predetermined value, the rubber is taken out of the chamber and cooled down. The rubber thus treated is kneaded again. Thus, the conventional kneading apparatus suffers from a difficulty that the kneading operation is low in efficiency.